vec2TLmom {lmomco} | R Documentation

## Convert a Vector of TL-moments to a TL-moment Object

### Description

This function converts a vector of trimmed L-moments (TL-moments) to a TL-moment object of this package. The object is an R `list`. This function is intended to facilitate the use of TL-moments that the user might have from other sources. The first five TL-moments are supported (λ^{(t)}_1, λ^{(t)}_2, λ^{(t)}_3, λ_4, λ^{(t)}_5, tau^{(t)}, tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5). Because in typical practice, the k >= 3 order L-moments are dimensionless ratios (tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5), this function computes λ^{(t)}_3, λ^{(t)}_4, λ^{(t)}_5 from λ^{(t)}_2 and the ratios. However, typical practice is not set on the use of λ^{(t)}_2 or tau^{(t)} as measure of dispersion. Therefore, this function takes an `lscale` optional logical (`TRUE|FALSE`) argument—if λ^{(t)}_2 is provided and `lscale=TRUE`, then tau is computed by the function and if tau is provided, then λ^{(t)}_2 is computed by the function. The trim level of the TL-moment is required.

### Usage

    vec2TLmom(vec,trim,lscale)

### Arguments

`vec` | A vector of L-moment values in λ^{(t)}_1, λ^{(t)}_2 or tau^{(t)}, tau^{(t)}_3, tau^{(t)}_4, and tau^{(t)}_5 order.
`trim` | The trimming level of the TL-moments (can be zero for the ordinary L-moments.)
`lscale` | A logical switch on the type of the second value of first argument. L-scale (λ_2) or LCV (tau). Default is `TRUE`, the second value in the first argument is λ_2.

### Value

An R `list` is returned where t represents the `trim` level.

`lambdas` | Vector of the TL-moments. First element is λ^{(t)}_1, second element is λ^{(t)}_2, and so on.
`ratios` | Vector of the L-moment ratios. Second element is tau^{(t)}, third element is tau^{(t)}_3 and so on.
`trim` | Level of symmetrical trimming used in the computation. Default is 0—the usual L-moments are returned.
`source` | An attribute identifying the computational source of the L-moments: “TLmoms”.

### Note

It is important to note that the “TL-moment object” returned by `TLmoms` is different in structure to that returned by `TLmoms`, and similar as the TL-moments should not be confused with the ordinary L-moments. Implementation in the package might change. At present asymmetrical TL-moment construction using this function is not available.s

### Author(s)

W.H. Asquith

### See Also

`lmom.ub`, `TLmoms`, `vec2lmom`

### Examples

    TL <- vec2TLmom(c(12,0.6,0.34,0.20,0.05),lscale=FALSE,trim=1)

[Package lmomco version 0.92 Index]